Conifers produce a diverse array of diterpenoids as major oleoresin components that play a role in the chemical defense against herbivores and pathogens, such as bark beetles and their associated fungi (Trapp et al. (2001) Annu. Rev. Plant Physiol. Plant Mol. Biol., 52:689-724; Keeling et al. (2006) Phytochemistry, 67:2415-2423; Keeling et al. (2006) New Phytol., 170:657-675). Oleoresin diterpenoids are also used as large-volume, renewable raw material for the production of a suite of industrial resins and coatings, and other bioproducts (Bohlmann et al. (2008) Plant J., 54:656-669; Hillwig et al. (2011) Biopolymer, 95:71-76). There is a need for alternative methods for producing diterpenoids.